An example of an existing air conditioner is a building type multi-split air conditioner to which an air conditioning apparatus is applied, the air conditioning apparatus being configured to perform a cooling operation or heating operation while delivering cooling energy or heating energy to an air conditioning target area, such as a room, by circulating a refrigerant between an outdoor unit, serving as a heat source unit, disposed outside the room and an indoor unit disposed in the room (refer to, for example, Patent Literature 1). As regards the refrigerant used in such an air conditioning apparatus, for example, an HFC-based refrigerant has been usually used. Further, a natural refrigerant, such as carbon dioxide (CO2), has recently been used.
In addition, there exists an air conditioning apparatus with another configuration, typified by a chiller system. In this air conditioning apparatus, cooling energy or heating energy is generated in a heat source unit disposed outside a room, the cooling energy or heating energy is transferred to a heat medium, such as water or antifreeze solution, in a heat exchanger disposed in an outdoor unit, and this is delivered to a fan coil unit, a panel heater, or the like, serving as an indoor unit disposed in an air conditioning target area to perform the cooling operation or heating operation (refer to, for example, Patent Literature 2). Further, there exists a waste heat recovery chiller in which four water pipes are connected to a heat source unit to supply cooling energy and heating energy.